I think I like the first one better, more fluid motion happening butt going targetward and arm going back. While your second vid is kind of choppy, stop, start, stop, start and not much counter motion happening. Swinging the hammer would help.

Your rear arm/shoulder is way out control, grab that broom stick with your left hand around shoulder high, stick it in the ground so the pole is just behind your rear toes and leverage your body forward from it. The broom stick should clear to the right tee side in backswing, it should not move away from target or toward the target but to the right. Then in forward swing the stick should make a quarter circle targetward, and never moving away from target. Your left arm is going way around your body targetward in backswing and then swinging way back away from target in forward swing. You want your left arm/shoulder to be your center or post to swing the right shoulder/arm/disc from and not really moving around whole a lot. The broom stick should really help.

Your rear hand ends up getting in front of your rear shoulder, so you aren't getting full leverage/swim ahead of it.

Sidewinder dropping some knowledge, this thread is solid. SW, just saying that all this with the stick and description of driving shoulders forward - from behind you - really helps it click for me. Now, the swim move makes complete sense. Without it, your lower half and upper half are fighting against one another. This should also improve posture.